A typical steer-by-wire power steering system may be hydrostatically or electrically actuated. Either configuration lacks a direct mechanical connection between the steering wheel, which receives a driver's steering command in the form of input steering torque, and the front wheels steered during a given steering maneuver. Steering input torque and steering wheel position signals are processed by an electronic control unit, which in turn generates a steering command signal as an output value. The steering command signal is transmitted to a steer-by-wire valve, which may then control an inlet of fluid to a steering actuator.
Conventional steer-by-wire power steering systems may at times provide a less than optimal steering response or torque “feel”, i.e., the torque response perceived by a driver of a vehicle via the steering wheel. Additionally, a reliable supply of electrical energy is essential to the proper functioning of any steer-by-wire system. Therefore, a power failure and/or main steering pump fault can render normal steering assistance temporarily unavailable. Depending on the design of the vehicle, such conditions may render the steering response less than optimal.